Reciprocating engine

ABSTRACT

A reciprocating engine includes a crankshaft and a connecting rod rotatably coupled to the crankshaft. The connecting rod defines a fluid passage extending along a length thereof. The reciprocating engine also includes a piston dome coupled to the connecting rod, the piston dome defining an inlet in fluid communication with the fluid passage of the connecting rod for receiving a fluid from the fluid passage of the connecting rod, a cooling passage in fluid communication with the inlet for circulating the fluid through the piston dome, and an exit in fluid communication with the cooling passage.

FIELD

The present disclosure generally relates to a reciprocating engine, andmore particularly to a reciprocating engine with built-in coolingfeatures for a piston dome.

BACKGROUND

Reciprocating engines generally include a crankshaft coupled to aplurality of piston domes through a respective plurality of connectingrods. Each of the piston domes are slidably positioned within respectivecylinders. Combustion within the respective cylinders causes the pistondomes to move along a longitudinal direction of the respectivecylinders, driving the connecting rods to rotate the crankshaft.Lubrication oil is routed to each of the cylinders and may be sprayed,e.g., onto a cold side of each of the piston domes. The lubrication oilprovides lubrication for the piston domes sliding along the longitudinaldirection of the respective cylinders.

However, with such a configuration the lubrication oil does not providesignificant cooling of the piston dome. The inventors of the presentdisclosure have discovered that it may be beneficial to configure areciprocating engine such that the lubrication oil, or other lubricatingfluid, provides increased cooling of the piston domes during operation.Accordingly, such a configuration would be useful.

BRIEF DESCRIPTION

Aspects and advantages of the invention will be set forth in part in thefollowing description, or may be obvious from the description, or may belearned through practice of the invention.

In one exemplary embodiment of the present disclosure, a reciprocatingengine is provided. The reciprocating engine includes a crankshaft and aconnecting rod rotatably coupled to the crankshaft. The connecting roddefines a fluid passage extending along a length thereof. Thereciprocating engine also includes a piston dome coupled to theconnecting rod, the piston dome defining an inlet in fluid communicationwith the fluid passage of the connecting rod for receiving a fluid fromthe fluid passage of the connecting rod, a cooling passage in fluidcommunication with the inlet for circulating the fluid through thepiston dome, and an exit in fluid communication with the coolingpassage.

In certain exemplary embodiments, the crankshaft defines a fluidpassage, and wherein the fluid passage of the crankshaft is fluidlycoupled to the fluid passage of the connecting rod.

For example, in certain exemplary embodiments, the reciprocating enginefurther includes a fluid pump coupled to and driven by the crankshaft,the fluid pump configured to provide a flow of fluid to the fluidpassage in the crankshaft.

For example, in certain exemplary embodiments the connecting rod definesa first end and a second end, wherein the connecting rod is rotatablycoupled to the crankshaft at the first end and coupled to the pistondome at the second end, and wherein the fluid passage of the connectingrod extends from the first end to the second end.

For example, in certain exemplary embodiments the crankshaft includes acrankpin journal, wherein the connecting rod includes an attachment endextending around the crankpin journal, wherein the crankpin journaldefines at least one opening fluidly connected to the fluid passage ofthe crankshaft, wherein the attachment end defines an annulus in fluidcommunication with the fluid passage of the connecting rod and extendingaround the at least one opening to fluidly connect the fluid passage ofthe crankshaft to the fluid passage of the connecting rod.

In certain exemplary embodiments the connecting rod is a firstconnecting rod, wherein the piston dome is a first piston dome. Withsuch an exemplary embodiment, the reciprocating engine may furtherinclude a second connecting rod rotatably coupled to the crankshaft, thesecond connecting rod defining a fluid passage extending along a lengththereof; and a second piston dome coupled to the second connecting rod,the second piston dome defining an inlet in fluid communication with thefluid passage of the second connecting rod, a cooling passage, and anexit.

For example, in certain exemplary embodiments the crankshaft defines afluid passage, and wherein the fluid passage of the crankshaft isfluidly connected to the fluid passage of the first connecting rod andthe fluid passage of the second connecting rod.

For example, with certain exemplary embodiments the crankshaft defines afirst fluid passage fluidly connected to the fluid passage of the firstconnecting rod, and wherein the crankshaft additionally defines aseparate, second fluid passage fluidly connected to the fluid passage ofthe second connecting rod.

In certain exemplary embodiments, the reciprocating engine furtherincludes a heat exchanger configured to receive fluid from the exitdefined by the piston dome.

For example, in certain exemplary embodiments, the reciprocating enginemay further include an oil pan, wherein the heat exchanger is thermallyconnected to the oil pan.

In certain exemplary embodiments the piston dome further defines aplurality of exits.

For example, in certain exemplary embodiments the piston dome includes aplurality of spray nozzles, and wherein the plurality of spray nozzlesdefine the plurality of exits.

For example, in certain exemplary embodiments, the reciprocating enginefurther includes a cylinder including a cylindrical wall, wherein thepiston dome is positioned within the cylinder, and wherein the pluralityof spray nozzles of the piston dome are configured to spray fluid ontothe cylindrical wall of the cylinder.

In certain exemplary embodiments the piston dome includes a hot side anda cold side, and wherein the cooling passage defined by the piston domeincludes at least a portion extending proximate the hot side of thepiston dome to allow the fluid therein to accept heat from the hot sideof the piston dome.

In another exemplary embodiment of the present disclosure a pistonassembly for a reciprocating engine is provided. The piston assemblyincludes a connecting rod extending between a first end and a secondend, the connecting rod defining a fluid passage extending from thefirst end to the second end. The piston assembly additionally includes apiston dome coupled to the connecting rod at the second end of theconnecting rod, the piston dome defining an inlet in fluid communicationwith the fluid passage of the connecting rod for receiving a fluid fromthe fluid passage of the connecting rod, a cooling passage in fluidcommunication with the inlet for circulating the fluid through thepiston dome, and an exit in fluid communication with the coolingpassage.

In certain exemplary embodiments the piston dome includes a hot side anda cold side, and wherein the cooling passage defined by the piston domeincludes at least a portion extending proximate the hot side of thepiston dome to allow the fluid therein to accept heat from the hot sideof the piston dome.

In certain exemplary embodiments the connecting rod defines a first endand a second end, wherein the connecting rod is configured to berotatably coupled to a crankshaft of the reciprocating engine at thefirst end and coupled to the piston dome at the second end.

For example, in certain exemplary embodiments the connecting rodincludes an attachment end at the first end, and wherein the attachmentend defines an annulus in fluid communication with the fluid passage ofthe connecting rod and configured to extend around one or more openingsdefined in a crankpin journal of the crankshaft to fluidly connect thefluid passage of the crankshaft to the fluid passage of the connectingrod.

In certain exemplary embodiments the piston dome further defines aplurality of exits.

For example, in certain exemplary embodiments the piston dome includes aplurality of spray nozzles, and wherein the plurality of spray nozzlesdefine the plurality of exits.

These and other features, aspects and advantages of the presentinvention will become better understood with reference to the followingdescription and appended claims. The accompanying drawings, which areincorporated in and constitute a part of this specification, illustrateembodiments of the invention and, together with the description, serveto explain the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including thebest mode thereof, directed to one of ordinary skill in the art, is setforth in the specification, which makes reference to the appendedfigures, in which:

FIG. 1 is a schematic, end view of a reciprocating engine in accordancewith an exemplary embodiment of the present disclosure.

FIG. 2 is a side, schematic view of at least a section of the exemplaryreciprocating engine of FIG. 1.

FIG. 3 is a close-up, cross-sectional view of a section of the exemplaryreciprocating engine of FIG. 1.

FIG. 4 is a side, schematic view of at least a section of areciprocating engine in accordance with another exemplary embodiment ofthe present disclosure.

DETAILED DESCRIPTION

Reference will now be made in detail to present embodiments of theinvention, one or more examples of which are illustrated in theaccompanying drawings. The detailed description uses numerical andletter designations to refer to features in the drawings. Like orsimilar designations in the drawings and description have been used torefer to like or similar parts of the invention.

As used herein, the terms “first”, “second”, and “third” may be usedinterchangeably to distinguish one component from another and are notintended to signify location or importance of the individual components.

The terms “upstream” and “downstream” refer to the relative directionwith respect to a flow in a pathway. For example, with respect to afluid flow, “upstream” refers to the direction from which the fluidflows, and “downstream” refers to the direction to which the fluidflows. However, the terms “upstream” and “downstream” as used herein mayalso refer to a flow of electricity.

The singular forms “a”, “an”, and “the” include plural references unlessthe context clearly dictates otherwise.

Approximating language, as used herein throughout the specification andclaims, is applied to modify any quantitative representation that couldpermissibly vary without resulting in a change in the basic function towhich it is related. Accordingly, a value modified by a term or terms,such as “about”, “approximately”, and “substantially”, are not to belimited to the precise value specified. In at least some instances, theapproximating language may correspond to the precision of an instrumentfor measuring the value, or the precision of the methods or machines forconstructing or manufacturing the components and/or systems. Forexample, the approximating language may refer to being within a tenpercent margin.

Here and throughout the specification and claims, range limitations arecombined and interchanged, such ranges are identified and include allthe sub-ranges contained therein unless context or language indicatesotherwise. For example, all ranges disclosed herein are inclusive of theendpoints, and the endpoints are independently combinable with eachother.

Referring now to the drawings, wherein identical numerals indicate thesame elements throughout the figures, FIG. 1 provides a schematic, endview of a reciprocating engine 10 in accordance with an exemplaryembodiment of the present disclosure. More specifically, thereciprocating engine 10 of FIG. 1 is configured as an internalcombustion engine of the reciprocating piston type having at least afirst cylinder 12 and a second cylinder 14. More specifically, theexemplary reciprocating engine 10 includes a first row of cylinders 16and a second row of cylinders 18 arranged in the form of a V-shapeddesign. Further, the reciprocating engine 10 includes at least a firstpiston dome 20 working within the first cylinder 12 and a second pistondome 22 working within the second cylinder 14. The first and secondpistons domes 20, 22 are connected by way of a first connecting rod 24and a second connecting rod 26, respectively, to a crankshaft 28.Further, the reciprocating engine 10 includes an oil pan 32 at a bottomend to collect a fluid provided during operation of the reciprocatingengine 10, as will be discussed in greater detail below. Notably, incertain embodiments, the fluid may be a lubrication fluid, such as alubricating oil. However, in other exemplary embodiments, the fluid maybe any other suitable fluid capable of transferring heat betweencomponents.

Referring now also to FIG. 2, a side, schematic view is provided of atleast a section of the exemplary reciprocating engine 10 described abovewith reference to FIG. 1. As is depicted, the exemplary reciprocatingengine 10 further includes a third cylinder (not depicted) and thirdpiston dome 36 connected to crankshaft 28 through a third connecting rod38, as well as a fourth cylinder (not depicted) and fourth piston dome42 connected to the crankshaft 28 through a fourth connecting rod 44. Itwill be appreciated, however, that although the exemplary reciprocatingengine 10 depicted includes four cylinders arranged in a V-shape, inother exemplary embodiments, the reciprocating engine 10 may include anyother number cylinders (such as two cylinders, six cylinders, eightcylinders, etc.), arranged in any suitable manner (e.g., in-line).

During operation, the crankshaft 28 is generally rotated about alongitudinal axis 46 in a direction 48 (see FIG. 1). Further, each ofthe respective connecting rods 24, 26, 38, 44 includes an attachment endand are rotatably coupled to the crankshaft 28 at a location offset fromthe longitudinal axis 46 of the crankshaft 28 at the respectiveattachment ends 50. Specifically, the crankshaft 28 includes a firstcrankpin journal 50 with a first attachment end 52 of the firstconnecting rod 24 rotatably coupled thereto; a second crankpin journal54 with a second attachment end 56 of the second connecting rod 26rotatably coupled thereto; a third crankpin journal 58 with a thirdattachment end 60 of the third connecting rod 38 rotatably coupledthereto; and a fourth crankpin journal 62 with a fourth attachment end64 of the fourth connecting rod 44 rotatably coupled thereto. Notably,each of the crankpin journals 50, 54, 58, 62 (depicted in phantom inFIG. 2) is offset from the longitudinal axis 46 of the crankshaft 28.

Further, as previously discussed, coordinated combustion within thecylinders 12, 14, 34, 40 causes the respective pistons 20, 22, 36, 42 tomove along a longitudinal direction of the respective cylinders 12, 14,34, 40, driving rotation of the crankshaft 28 in the direction 48 (FIG.1). The crankshaft 28 may be coupled to a component through anattachment flange 66 position at a longitudinal end of the crankshaft 28such that the crankshaft 28 may transfer work to such component. Forexample, in certain exemplary embodiments, the reciprocating engine 10may be configured for installation within a motor vehicle, such that theattachment flange 66 is coupled to, e.g., a flywheel or other componentfor powering motor vehicle. However, in other embodiments, the exemplaryreciprocating engine 10 may be utilized in any other suitable machine orin any other suitable scenario. For example, in other exemplaryembodiments, the reciprocating engine 10 may be utilized for, e.g.,power generation, as a fluid pump, as a starter motor for an aircraft,etc.

As briefly noted above, the present reciprocating engine 10 includescertain features built-in for allowing fluid to more effectively providecooling of the piston domes 20, 22, 36, 42 during operation of thereciprocating engine 10. Specifically, for the embodiment depicted, thecrankshaft 28 defines a fluid passage 68 enclosed therein (denoted bydotted lines 68, see also FIG. 3, discussed below) for receiving,transferring, and providing, fluid to certain components of thereciprocating engine 10. More specifically, the exemplary reciprocatingengine 10 depicted further includes a fluid pump 70 coupled to thecrankshaft 28 and configured to provide a flow of fluid to the fluidpassage 68 in the crankshaft 28. Notably, by coupling the fluid pump 70to the crankshaft 28, the fluid pump 70 may provide a variable amount offluid to the fluid passage 68 within the crankshaft 28 based on, e.g., arotational speed of the crankshaft 28. It will be appreciated that anysuitable fluid pump 70 may be provided. For example, in certainexemplary embodiments, the fluid pump 70 could be a centrifugal pump, avane pump, a hose type drum pump, a gear pump, etc. Additionally, itwill be appreciated that in other exemplary embodiments, the fluid pump70 may instead be coupled elsewhere, and/or driven by any other suitablemeans (e.g., may be configured as an electric fluid pump).

Furthermore, for the embodiment depicted, each of the respectiveconnecting rods 24, 26, 38, 44 also define a fluid passage extendingalong a length thereof, and similarly, for the embodiment depicted, eachof the respective piston domes 20, 22, 36, 42 also define a coolingpassage therein. More specifically, the first connecting rod 24 definesa fluid passage 72 extending substantially along a length thereof, thesecond connecting rod 26 defines a fluid passage 74 extendingsubstantially along a length thereof, the third connecting rod 38defines a fluid passage 76 extending substantially along the lengththereof, and the fourth connecting rod 44 defines a fluid passage 78extending substantially along a length thereof. Further, the firstpiston dome 20 defines a cooling passage 80 therein, the second pistondome 22 defines a cooling passage 82 therein, the third piston dome 36defines a cooling passage 84 therein, and the fourth piston dome 42defines a cooling passage 86 therein. The fluid passage 68 of thecrankshaft 28 is, for the embodiment depicted, fluidly connected to thefluid passages 72-78 of each of the respective connecting rods 24, 26,38, 44, and the fluid passages 72-78 of each of the respectiveconnecting rods 24, 26, 38, 44 are fluidly connected to the coolingpassages 80-86 of each of the respective piston domes 20, 22, 36, 42.

Referring now to FIG. 3, such features and functionality will bedescribed in greater detail. FIG. 3 provides a close-up, cross-sectionalview of a section of the exemplary reciprocating engine 10 describedabove. More specifically, FIG. 3 provides a close-up, cross-sectionalview of the first piston dome 20 (within the first cylinder 12) andfirst connecting rod 24 coupled to the first crankpin journal 50 of thecrankshaft 28.

As stated, the crankshaft 28 defines a fluid passage 68 therein.Additionally, the first connecting rod 24 defines the fluid passage 72extending substantially along a length thereof. More specifically, thefirst connecting rod 24 defines a first end 88 and a second end 90. Theattachment end 52 of the first connecting rod 24 is at the first end 88,such that the first connecting rod 24 is rotatably coupled to the firstcrankpin journal 50 of the crankshaft 28 at the first end 88. Further,the first connecting rod 24 is coupled to the first piston dome 20 atthe second end 90. More specifically, the first piston dome 20 includesa pin 92 with the second end 90 of the first connecting rod 24 rotatablycoupled to the pin 92 of the first piston dome 20. The fluid passage 72of the first connecting rod 24 extends from the first end 88 to thesecond end 90. Notably, in certain embodiments, one or both of the firstend 88/attachment end 52 and a second end 90 may be formed of two ormore components to attach the first connecting rod 24 to the firstcrankpin journal 50 and/or to the pin 92. Alternatively, however, one orboth of the crankshaft 28 and first piston dome 20 may be assembledthrough the first end 88/attachment and 52 and/or the second end 90 ofthe first connecting rod 24.

Referring still to FIG. 3, the fluid passage 68 of the crankshaft 28 isfluidly connected to the fluid passage 72 of the first connecting rod24. Specifically, for the embodiment depicted, the first crankpinjournal 50 defines at least one opening 94, and more particularly, forthe embodiment depicted defines a plurality of circumferentially spacedopenings 94 fluidly connected to the fluid passage 68 of the crankshaft28. Additionally, the attachment end 52 of the first connecting rod 24defines an annulus 96 surrounding the first crankpin journal 50 and,more particularly, extending around the at least one opening 94, orrather around the plurality of circumferentially spaced openings 94 ofthe first crankpin journal 50. The annulus 96 defined at the attachmentend 52 of the first connecting rod 24 therefore fluidly connects thefluid passage 68 of the crankshaft 28 to the fluid passage 72 of thefirst connecting rod 24.

Further, as briefly stated above, the first piston dome 20 defines thecooling passage 80. More specifically, the first piston dome 20 definesan inlet 98 in fluid communication with the fluid passage 72 of thefirst connecting rod 24 for receiving fluid from the fluid passage 72 ofthe first connecting rod 24, the cooling passage 80 in fluidcommunication with the inlet 98 for circulating the fluid receivedthrough the inlet 98, and an exit 100 in fluid communication with thefluid passage 72 for ejecting the fluid circulated through the coolingpassage 80. As is depicted, the inlet 98 may be fluidly connected to thefluid passage 72 of the first connecting rod 24 in substantially thesame manner that the fluid passage 68 of the crankshaft 28 is fluidlyconnected to the fluid passage 72 of the first connecting rod 24.

It will be appreciated that the first piston dome 20 generally includesa hot side 102 and a cold side 104. The hot side wanted to is exposed tothe combustion within the first cylinder 12, which drives the firstpiston dome 20 along a longitudinal centerline of the first cylinder 12.For the embodiment depicted, the cooling passage 80 defined by the firstpiston dome 20 includes at least a portion extending proximate the hotside 102 of the first piston dome 20 to allow the fluid therein toaccept heat from the hot side 102 of the first piston dome 20. In such amanner, the configuration of the cooling passage 80 may more effectivelyremove heat from the first piston dome 20 and may maintain a temperatureof the first piston dome 20 within a desired operating range. Notably,as used herein, the term “proximate” with respect to the position of thecooling passage 80 refers to the cooling passage 80 being closer to thehot side 102 than the cold side 104.

Furthermore, as stated, the exit 100 defined by the first piston dome 20is configured to eject the fluid circulated through the cooling passage80. More specifically, for the embodiment depicted, the first pistondome 20 further defines a plurality of exits 100. More specifically,still, the first piston dome 20 includes a plurality of spray nozzles106, and the plurality of spray nozzles 106 define the plurality ofexits 100. The first cylinder 12, within which the first piston dome 20is positioned, includes a cylinder wall 108 and the plurality of spraynozzles 106 of the first piston dome 20 are configured to spray thefluid previously circulated through the first piston dome 20 onto thecylinder wall 108 of the first cylinder 12. In such a manner, the fluidmay lubricate the first cylinder 12 and first piston dome 20. Notably,however, in other embodiments, the fluid may exit the first piston dome20 in any other suitable manner. For example, in other embodiments, thefluid exit(s) 100 may not include spray nozzles 106 and instead maysimply be opening allowing the fluid flow out of the respective pistondome and fall down to, e.g., the oil pan 32.

Accordingly, it will be appreciated, that as used herein, the term“fluid” may refer to any fluid capable of performing the functionsherein. For example, in certain exemplary embodiments, the fluid may bea lubrication fluid capable of providing lubrication to the variouscomponents within the reciprocating engine 10, as well as functioning asa heat exchange fluid. Accordingly, the fluid may be any suitablelubrication oil, or other fluid known in the art, or later developed.However, in other exemplary embodiments, the fluid may instead be anyother fluid capable of functioning as a heat exchange fluid.

Moreover, as is further shown in the exemplary embodiment of FIG. 3, theengine 10 further includes a plurality of crankshaft bearings 109rotatably supporting the crankshaft 28. The bearings 109 may be anysuitable type of bearings (e.g., ball bearings, roller bearings, taperedroller bearings, ceramic, stainless steel, etc.). It will further beappreciated that the fluid from the exit(s) 100 may provide lubricationto the bearings in addition to cooling the piston domes 20, 22, 36, 40.

Referring now back specifically to FIG. 2, it will be appreciated that,for the embodiment depicted, each of the second, third, and fourthconnecting rods 26, 38, 44 are configured in a similar manner as thefirst connecting rod 24, and similarly, each of the second, third, andfourth piston domes 22, 36, 40 are configured similarly to the firstpiston dome 20. More specifically, for the embodiment depicted, each ofthe second, third, and fourth connecting rods 26, 38, 44 are rotatablycoupled to the crankshaft 28 and define the fluid passages 74, 76, 78,each extending substantially along respective lengths thereof.Additionally, each of the second, third, and fourth piston domes 22, 36,40 are coupled to the respective connecting rod 26, 38, 44 and eachdefines an inlet in fluid communication with the fluid passage of therespective connecting rod, a cooling passage, and an exit (not labeled).

As briefly stated above, the fluid passage 68 of the crankshaft 28 isfluidly connected to the fluid passages 72, 74, 76, 78 of each of theplurality of connecting rods 24, 26, 38, 44. Specifically, the fluidpassage 68 of the crankshaft 28 is fluidly connected to the fluidpassage 72 of the first connecting rod 24, the fluid passage 74 of thesecond connecting rod 26, the fluid passage 76 of the third connectingrod 38, and the fluid passage 78 of the fourth connecting rod 44. Forexample, in certain embodiments, each of the second crankpin journal 54,third crankpin journal 58, and fourth crankpin journal 62 may define oneor more openings (not labeled) configured to provide the fluid to thefluid passages 74, 76, 78 in the respective second connecting rod 26,third connecting rod 38, and fourth connecting rod 44 in a mannersimilar to that shown in FIG. 2. Further, in order to ensure each of theplurality of piston domes 20, 22, 36, 42 receive a desired amount offluid, such openings in the crankpin journals may be numbered and sizedto meter the flow of fluid therethrough to the fluid passages 72, 74,76, 78 in the respective connecting rods 24, 26, 38, 44.

Also, given the configuration described herein wherein the fluid mayaccept a substantial amount of heat from the piston domes 20, 22, 36,42, an additional heat exchanger may be beneficial to remove additionalheat from such fluid. Accordingly, for the embodiment depicted, thereciprocating engine 10 further includes a heat exchanger 120. The heatexchanger 120 is configured to receive fluid ejected from the exits(such as exit 100; FIG. 3) of the plurality of piston domes 20, 22, 36,42. The heat exchanger 120 may be thermally connected to the oil pan 32(as depicted in phantom in FIG. 1), such that it is dedicated toremoving heat from the fluid.

It should be appreciated, however, that the exemplary embodimentdepicted in FIGS. 2 and 3 is by way of example only. In other exemplaryembodiments, the reciprocating engine 10 may have any other suitableconfiguration. For example, in other exemplary embodiments, the fluidpassages in the connecting rods may be fluidly connected to the fluidpassage in the crankshaft 28 in any other suitable manner, andsimilarly, the fluid passages in the connecting rods may be fluidlyconnected to the cooling passages in the respective piston domes in anyother suitable manner. Further, in still other exemplary embodiments,the fluid passages in the connecting rods may be configured to receivefluid from a source other than the fluid passage in crankshaft 28.Accordingly, in certain exemplary embodiments, the fluid passages in theconnecting rods may not be fluidly connected to the fluid passage in thecrankshaft. Furthermore, in still other embodiments, the engine 10 maynot include a heat exchanger for the fluid in the oil pan 32 (andfurther may not include an oil pan 32) and instead may use any othersuitable thermal management system (if any at all).

Moreover, it should be appreciated that in other exemplary embodiments,the crankshaft 28 may have still other suitable configurations. Forexample, referring now briefly to FIG. 4, providing a side, schematicview of a section of a reciprocating engine 10 in accordance withanother exemplary embodiment of the present disclosure, the fluidpassage defined by the crankshaft 28 may not extend between each of theplurality of connecting rods 24, 26, 38, 44 (as is the case with theexemplary reciprocating engine 10 described above with reference to FIG.2). More specifically, for the embodiment of FIG. 4 the fluid passage ofthe crankshaft 28 is not configured as a continuous fluid passage, andis not directly fluidly connected with the fluid passages 72, 74, 76, 78of each of the connecting rods 24, 26, 38, 44. Instead, for theembodiment of FIG. 4, the crankshaft 28 defines a plurality of separatefluid passages. More specifically, for the embodiment depicted, thecrankshaft 28 defines a first fluid passage 110 fluidly connected to thefluid passage 72 of the first connecting rod 24, a second fluid passage112 fluidly connected to the fluid passage 74 of the second connectingrod 26, a third fluid passage 114 fluidly connected to the fluid passage76 of the third connecting rod 38, and a fourth fluid passage 116fluidly connected to the fluid passage 78 of the fourth connecting rod44.

Notably, for the embodiment of FIG. 4, the reciprocating engine 10 doesnot include a dedicated fluid pump coupled to the crankshaft 28 (see,e.g., fluid pump 70 discussed above). Instead, the crankshaft 28includes a plurality of openings 118 for each of the respectiveplurality of fluid passages 110, 112, 114, 116 to receive fluidtherethrough.

It will be appreciated that in certain exemplary embodiments, one ormore components of the reciprocating engine 10 described herein may bemanufactured or formed using any suitable process. However, inaccordance with several aspects of the present subject matter, one ormore components of the reciprocating engine 10 described herein may beformed using an additive-manufacturing process, such as a 3-D printingprocess. For example, in certain exemplary embodiments, one or more ofthe crankshaft 28, connecting rods 24, 26, 38, 44, and/or piston domes20, 22, 36, 42 may be formed using an additive manufacturing processsuch that they may define the respective fluid passages and coolingpassages therein.

The use of such a process may allow the one or more components of thereciprocating engine 10 to be formed to include a variety of featuresnot possible when using prior manufacturing methods (e.g., certainfeatures of the respective fluid passages). For example, the additivemanufacturing methods described herein enable the manufacture ofcomponents having unique features, configurations, thicknesses,materials, densities, fluid passageways, cooling passageways, andmounting structures not possible using prior manufacturing methods. Someof these novel features are described herein.

As used herein, the terms “additively manufactured” or “additivemanufacturing techniques or processes” refer generally to manufacturingprocesses wherein successive layers of material(s) are provided on eachother to “build-up,” layer-by-layer, a three-dimensional component. Thesuccessive layers generally fuse together to form a monolithic componentwhich may have a variety of integral sub-components. Although additivemanufacturing technology is described herein as enabling fabrication ofcomplex objects by building objects point-by-point, layer-by-layer,typically in a vertical direction, other methods of fabrication arepossible and within the scope of the present subject matter. Forexample, although the discussion herein refers to the addition ofmaterial to form successive layers, one skilled in the art willappreciate that the methods and structures disclosed herein may bepracticed with any additive manufacturing technique or manufacturingtechnology. For example, embodiments of the present invention may uselayer-additive processes, layer-subtractive processes, or hybridprocesses.

Suitable additive manufacturing techniques in accordance with thepresent disclosure include, for example, Fused Deposition Modeling(FDM), Selective Laser Sintering (SLS), 3D printing such as by inkjets,laser jets, and binder jets, Sterolithography (SLA), Direct SelectiveLaser Sintering (DSLS), Electron Beam Sintering (EBS), Electron BeamMelting (EBM), Laser Engineered Net Shaping (LENS), Laser Net ShapeManufacturing (LNSM), Direct Metal Deposition (DMD), Digital LightProcessing (DLP), Direct Selective Laser Melting (DSLM), Selective LaserMelting (SLM), Direct Metal Laser Melting (DMLM), and other knownprocesses.

In addition, one skilled in the art will appreciate that a variety ofmaterials and methods for bonding those materials may be used and arecontemplated as within the scope of the present disclosure. As usedherein, references to “fusing” may refer to any suitable process forcreating a bonded layer of any of the above materials. For example, ifthe material is powdered metal, the bond may be formed by a melting orsintering process. One skilled in the art will appreciate that othermethods of fusing materials to make a component by additivemanufacturing are possible, and the presently disclosed subject mattermay be practiced with those methods.

In addition, the additive manufacturing processes disclosed herein allowa single component to be formed from multiple materials. Thus, thecomponents described herein may be formed from any suitable mixtures ofthe above materials. For example, a component may include multiplelayers, segments, or parts that are formed using different materials,processes, and/or on different additive manufacturing machines. In thismanner, components may be constructed which have different materials andmaterial properties for meeting the demands of any particularapplication. In addition, although the components described herein areconstructed entirely by additive manufacturing processes, it should beappreciated that in alternate embodiments, all or a portion of thesecomponents may be formed via casting, machining, and/or any othersuitable manufacturing process. Indeed, any suitable combination ofmaterials and manufacturing methods may be used to form thesecomponents.

Referring to FIGS. 2 through 4, generally embodiments of the presentdisclosure are provided wherein fluid is provided through a fluidpassage 68 in a crankshaft 28, to and through a fluid passage 72 in aconnecting rod 24, to a cooling passage 80 in a piston dome 20. For theembodiments shown, the fluid is a lubrication fluid that is subsequentlyprovided through exit(s) 100 of the piston dome 24 to a cylinder tolubricate, e.g., the cylinder walls 108. It should be appreciated,however, that in other exemplary embodiments, the fluid may notnecessarily be a lubrication fluid, and instead may be any suitable heatexchange fluid. For example, instead of the “open loop” systems shown,in other exemplary embodiments, the fluid delivery system to the pistondome(s) may be a closed loop system. More specifically, in otherexemplary embodiments, the fluid passage 68 may be a first, deliveryfluid passage through the crankshaft 28 and the fluid passage 72 may afirst, delivery fluid passage through the connecting rod 24. Theconnecting rod 24 may further define a second, return fluid passage(which may extend, e.g., parallel to the first fluid passage 72) andsimilarly the crankshaft 28 may define a second, return fluid passage(which may similarly extend, e.g., parallel to the first fluid passage68). The second fluid passage in the crankshaft 28 may be fluidlyconnected to the second fluid passage in the connecting rod 24 in asimilar manner that the first fluid passage 68 is connected to the firstfluid passage 72 (i.e., the connecting rod 24 may define a secondannulus surrounding one or more openings connected to the second passagein the crankshaft 28). Further, the second fluid passage in thecrankshaft 24 may be fluidly connected to the exits 100 of the pistondome 20 in a similar manner as the first fluid passage 72 is connectedto the inlet 98 of the piston dome 20. The fluid may be returned throughthe crankshaft 28 to, e.g., a heat exchanger, and then provided back toa fluid pump to recirculate the fluid.

This written description uses examples to disclose the invention,including the best mode, and also to enable any person skilled in theart to practice the invention, including making and using any devices orsystems and performing any incorporated methods. The patentable scope ofthe invention is defined by the claims, and may include other examplesthat occur to those skilled in the art. Such other examples are intendedto be within the scope of the claims if they include structural elementsthat do not differ from the literal language of the claims, or if theyinclude equivalent structural elements with insubstantial differencesfrom the literal languages of the claims.

What is claimed is:
 1. A reciprocating engine comprising: a cylindercomprising a cylinder wall; a crankshaft; a connecting rod rotatablycoupled to the crankshaft, the connecting rod defining a connecting rodfluid passage extending along a length thereof; and a piston assemblycomprising: a piston dome comprising a hot side and a cold side, thepiston dome coupled to the connecting rod and positioned within thecylinder, an inlet defined in the piston dome in fluid communicationwith the connecting rod fluid passage and configured to receive a fluidfrom the connecting rod fluid passage, a plurality of piston domecooling passages enclosed by the piston dome and configured to circulatethe fluid in a set directional flow through the piston dome, such thatthe piston dome cooling passage extends through the piston dome from theinlet, toward the hot side, proximate the hot side, and from proximatethe hot side toward a plurality of exits.
 2. The reciprocating engine ofclaim 1, wherein the plurality of exits corresponds with a plurality ofnozzles configured to spray the fluid onto the cylinder wall.
 3. Thereciprocating engine of claim 2, wherein each of the plurality ofnozzles is configured to spray the fluid directly onto the cylinderwall.
 4. The reciprocating engine of claim 1, further comprising atleast one branch point at which at least one of the plurality of pistondome cooling passages divides into at least two of the plurality ofpiston dome cooling passages.
 5. The reciprocating engine of claim 4,wherein the at least one branch point is disposed proximate the hot sideof the piston dome.
 6. The reciprocating engine of claim 1, wherein theconnecting rod is a first connecting rod defining a first connecting rodfluid passage, wherein the piston dome is a first piston dome defining afirst inlet, a first piston dome cooling passage and a first pluralityof exits defined by a first plurality of nozzles, and wherein thereciprocating engine further comprises: a second connecting rodrotatably coupled to the crankshaft, the second connecting rod defininga second connecting rod fluid passage; and a second piston dome coupledto the second connecting rod, the second piston dome defining a secondinlet in fluid communication with the second connecting rod fluidpassage, a second piston dome cooling passage, and a second plurality ofexits defined by a second plurality of nozzles.
 7. The reciprocatingengine of claim 6, wherein the crankshaft defines a crankshaft fluidpassage, and wherein the crankshaft fluid passage is fluidly connectedto each of the first connecting rod fluid passage and the secondconnecting rod fluid passage.
 8. The reciprocating engine of claim 6,wherein the crankshaft defines a first crankshaft fluid passage fluidlyconnected to the first connecting rod fluid passage, and wherein thecrankshaft additionally defines a separate, second crankshaft fluidpassage fluidly connected to the second connecting rod fluid passage. 9.The reciprocating engine of claim 1, further comprising a heat exchangerconfigured to receive the fluid from the exit defined by the pistondome.
 10. The reciprocating engine of claim 9, further comprising an oilpan, wherein the heat exchanger is in thermal communication with the oilpan.
 11. The reciprocating engine of claim 1, wherein the hot side ofthe piston dome is configured to be exposed to combustion within thecylinder, and wherein the piston dome cooling passage extendingproximate the hot side of the piston dome allows the fluid therein toaccept heat from the hot side of the piston dome.
 12. The reciprocatingengine of claim 11, wherein at least a first and a second one of theplurality of exits are disposed opposite one another relative to alongitudinal centerline of the cylinder.
 13. A piston assembly for areciprocating engine including a cylinder having a cylinder wall, thepiston assembly comprising: a piston dome comprising a hot side and acold side, an inlet defined in the piston dome configured to receive afluid from at least one other component of an engine, a plurality ofpiston dome cooling passages enclosed by the piston dome and configuredto circulate the fluid in a set directional flow through the pistondome, such that the piston dome cooling passage extends through thepiston dome from the inlet, toward the hot side, proximate the hot side,and from proximate the hot side toward a plurality of exits.
 14. Thepiston assembly of claim 13, wherein at least one of the plurality ofexits is disposed on the cold side of the piston dome.
 15. The pistonassembly of claim 13, wherein the plurality of exits corresponds with aplurality of nozzles configured to spray the fluid onto a cylinder wall.16. The piston assembly of claim 15, wherein each of the plurality ofnozzles is configured to spray the fluid directly onto the cylinderwall.
 17. The piston assembly of claim 13, further comprising at leastone branch point at which at least one of the plurality of piston domecooling passages divides into at least two of the plurality of pistondome cooling passages.
 18. The piston assembly of claim 17, wherein theat least one branch point is disposed proximate the hot side of thepiston dome.
 19. A method of cooling a piston assembly for areciprocating engine, the method comprising: receiving, with an inletdefined in a piston dome, a fluid from at least one other component ofan engine; circulating the fluid, through at least one of a plurality ofpiston dome cooling passages enclosed by the piston dome, in a setdirectional flow from the inlet towards a hot side of the piston dome;and ejecting the fluid with a plurality of exits in fluid communicationto proximate the hot side of the piston dome through at least some ofthe plurality of piston dome cooling passages.
 20. The method of claim19, further comprising: dividing, with at least one branch point, atleast one of the plurality of piston dome cooling passages into at leasttwo of the plurality of piston dome cooling passages.